Various types of industrial fluid filters have been developed in the past. For instance, one common type of fluid filter includes a vessel with an inlet for receiving fluid to be filtered and an outlet for discharging filtered fluid from the vessel. The fluid filter also includes a substantially flexible filter sleeve and a perforated metal basket for supporting the flexible filter sleeve against the pressure of fluid flow. In operation, fluid is directed into the interior of the filter sleeve from the inlet of the vessel. After passing through the filter sleeve and the basket, the fluid is discharged from the vessel through the outlet. The filtered-out particulate matter remains in the filter sleeve, which can be removed from the basket for cleaning and/or replacement.
The overall filtration capacity of fluid filters can be increased by providing them with a multi-component filter sleeve or multiple filter sleeves or bags. For example, Gershenson U.S. Pat. No. 6,030,531 discloses a filter bag insert having concentrically arranged inner and outer filter sleeves. The upper ends of the two filter sleeves are attached to each other via a single (i.e., common) cap. A perforated metal basket is provided for supporting the inner and outer filter sleeves against the pressure of fluid passing therethrough.
The filter bag insert disclosed in the Gershenson '531 patent suffers from various problems and disadvantages. For instance, as fluid passes through the inner and outer filter sleeves during a filtering operation, portions of the sleeves become lodged in the perforations of the basket, thereby causing the sleeves to “stick” to the basket. Because the inner and outer filter sleeves are attached to a single cap, they move simultaneously when the cap is lifted to remove the filter sleeves from the basket. In such circumstances, if both of the filter sleeves “stick” to the basket due to the pressure of fluid passing therethrough, a relatively large lifting force would have to be applied to the cap in order to dislodge the sleeves from the basket.
Rosaen U.S. Pat. No. 4,496,459 discloses a filter device which is equipped with a pair of concentric filter bag segments. While the filter bag segments are independently supported by way of separate rings, there is no disclosure in the Rosaen '459 patent of a mechanism for quickly and efficiently removing the filter bag segments from an associated filter basket.